1. Field of the Invention
The present invention relates a control system for canceling load unbalance of a three-phase circuit which is capable of preventing malfunction of an over-current grounding relay (OCGR) due to load unbalance in multiple direct grounding series distribution lines.
2. Description of the Related Art
A conventional closed circuit protector for a secondary side circuit of a current transformer receives as its input a secondary current of the current transformer to compare the secondary current thus inputted thereto with a predetermined current value within the closed circuit protector to thereby detect that a secondary circuit of the current transformer has been disconnected or opened, to form a closed circuit in the form of a short-circuit (refer to a page 1 and FIG. 1 of Japanese Patent Laid-Open No. 11-205998, for example).
The conventional device as described above has no function of comparing loads of phases A, B and C with one another to line these loads up in the order of decreasing load to thereby change a part of the load of the phase having a maximum current over to the load of the phase having a minimum current. Hence, there is a problem in that an over-current grounding relay (OCGR) undergoes malfunction due to load unbalance.